Stage alignment apparatus and its control method, exposure apparatus, and semiconductor device manufacturing method

ABSTRACT

A stage alignment apparatus includes a first moving member which moves in a first direction, a second moving member which moves in a second direction different from the first direction, a stage which is slidably supported by the first moving member and the second moving member and is guided in the first and second directions, a first control section which controls a posture of the first moving member in a third direction, the third direction being a direction rotatable about an axis substantially perpendicular to the first and second directions, and a second control section which controls a posture of the second moving member in the third direction on the basis of a signal which controls the posture of the first moving member in the third direction.

This application is a divisional application of U.S. patent applicationSer. No. 10/368,621, filed Feb. 20, 2003 now U.S. Pat. No. 6,975,383.

FIELD OF THE INVENTION

The present invention relates to a stage alignment apparatus for drivinga stage and its control method, an exposure apparatus, and asemiconductor device manufacturing method.

BACKGROUND OF THE INVENTION

Many apparatuses are used as an apparatus arranged to align an object ona stage in which the stage moves on a surface plate. Among suchapparatuses, there exists an apparatus which has two beam-like movingmembers that can move in two directions perpendicular to each other anda stage that moves in accordance with the moving members, and in whichthese moving members are guided in the respective directions by guidesto drive the stage. This type of apparatus has motors which drive amoving member at the two ends thereof, and the motors with an excellentdriving capability can be arranged. Hence, a stage can be moved at highspeed. Since the stage and the motors are separated from each other, themotors can efficiently be cooled. In this type of apparatus, however,the two moving members may thermally expand, each moving member and itsmotor may be different in parallelism, or the moving member may rotatein the horizontal direction. For this reason, the moving members andstage, which can inherently move relative to each other, are likely toexcessively constrain each other. When the moving members and stage fallinto this excessive constraint stage, they may come in contact with eachother to restrict mutual movement, or the alignment precision of thestage may degrade due to vibrations caused by interference between thetwo moving members.

In a method disclosed in Japanese Patent Laid-Open No. 9-34135, amechanical means is provided, and the fit tolerance of the first movingmember and stage is improved to tightly fit them with no play while thesecond moving member and stage are loosely fitted, thereby attempting tosolve the above-mentioned problem.

In a conventional method, however, new vibrations may occur by providinga mechanism such as a spring or the like. Additionally, control of oneof two moving members in a tight constraint state makes it difficult toalign a stage at high precision. Moreover, the mechanism such as aspring or the like between the second moving member and a bearingincreases the complexity of the apparatus.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theabove-mentioned problems, and has as its object to provide a stagealignment apparatus and its control method, an exposure apparatus, and asemiconductor device manufacturing method by, e.g., controlling theposture of the second moving member on the basis of a signal whichcontrols the posture of the first moving member.

According to the first aspect of the present invention, there isprovided a stage alignment apparatus characterized by comprising a firstmoving member which can move in a first direction, a second movingmember which can move in a second direction different from the firstdirection, a stage which is slidably supported by the first movingmember and second moving member and is guided in the first and seconddirections, a first control section which controls a posture, in a thirddirection different from the first and second directions, of the firstmoving member, and a second control section which controls a posture, inthe third direction, of the second moving member on the basis of asignal which controls the posture of the first moving member.

According to a preferred embodiment of the present invention, each ofthe first control section and second control section has a measurementsection which measures the posture of the moving member, and an actuatorwhich drives the moving member on the basis of a measurement resultobtained by the measurement section.

According to a preferred embodiment of the present invention, theactuator comprises a linear motor.

According to a preferred embodiment of the present invention, the secondcontrol section controls the posture of the second moving member on thebasis of a signal which controls the posture of the first moving memberfiltered by a predetermined filter.

According to a preferred embodiment of the present invention, the firstand second directions are perpendicular to each other, and the thirddirection is a rotational angle about an axis perpendicular to the firstand second directions.

According to a preferred embodiment of the present invention, the firstmoving member and second moving member are supported by guides arrangedsuch that their ends are parallel to the first and second directions,respectively, and a bearing which slides with a predetermined gap thatallows rotational displacement in the third direction with respect tothe guides and are guided in the first and second directions through theguides and bearing.

According to a preferred embodiment of the present invention, the firstcontrol section performs calculations of a proportional term, anintegral term, and a derivative term to obtain a signal which controlsthe posture of the first moving member, and the second control sectionperforms calculations of a proportional term and a derivative term toobtain the posture of the second moving member.

According to a preferred embodiment of the present invention, the firstcontrol section controls the posture of the first moving member on thebasis of a signal which controls the posture of the second movingmember.

According to the second aspect of the present invention, there isprovided a method of controlling a stage alignment apparatus for guidinga stage in a first direction and a second direction different from thefirst direction by a first moving member which can move in the firstdirection and a second moving member which can move in the seconddirection, characterized by comprising the first control step ofcontrolling a posture, in a third direction different from the first andsecond directions, of the first moving member, and the second controlstep of controlling the posture in the third direction of the secondmoving member on the basis of a signal which controls a posture of thefirst moving member.

According to a preferred embodiment of the present invention, in thefirst control step, the posture of the first moving member is controlledon the basis of a signal which controls a posture of the second movingmember.

According to the third aspect of the present invention, there isprovided an exposure apparatus characterized in that the exposureapparatus uses a stage alignment apparatus controlled by a controlmethod according to the present invention to transfer a pattern.

According to the fourth aspect of the present invention, there isprovided a semiconductor device manufacturing method characterized bycomprising the coating step of coating a substrate with a photosensitivemember, the exposure step of transferring a pattern onto the substratecoated with the photosensitive member in the coating step using anexposure apparatus according to the present invention, and thedevelopment step of developing the photosensitive member of thesubstrate on which the pattern is transferred in the exposure step.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention.

FIG. 1A is a block diagram showing the arrangement of a stage alignmentapparatus according to a preferred embodiment of the present invention;

FIG. 1B is a block diagram showing the arrangement of the stagealignment apparatus according to the preferred embodiment of the presentinvention;

FIG. 2 is a block diagram showing the arrangement of a control sectionwhich controls the Z-axis rotational displacements of an X moving memberand a Y moving member;

FIG. 3 is a graph showing a frequency characteristic of a filter in FIG.2;

FIG. 4 is a graph showing another frequency characteristic of the filterin FIG. 2;

FIG. 5 is a block diagram showing the arrangement of a control sectionwhich controls the Z-axis rotational displacements of an X moving memberand a Y moving member in the controller of a stage alignment apparatusaccording to the second preferred embodiment of the present invention;

FIG. 6 is a view showing the concept of an exposure apparatus used whena stage alignment apparatus of the present invention is applied to themanufacturing process of a semiconductor device;

FIG. 7 is a flow chart showing the flow of the whole manufacturingprocess of a semiconductor device; and

FIG. 8 is a flow chart showing the detailed flow of the wafer process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings.

[First Embodiment]

FIGS. 1A and 1B are views showing the schematic arrangement of a stagealignment apparatus according to a preferred embodiment of the presentinvention. FIG. 1A is a plan view of the stage alignment apparatus, andFIG. 1B, a perspective view of the stage alignment apparatus.

In FIG. 1A, the stage alignment apparatus has a surface plate 1, a stage2 which moves on the surface plate 1 through the surface plate 1 and abearing (not shown) (e.g., a hydrostatic bearing), a beam-like X movingmember 3 which guides the stage 2 in the Y direction, a beam-like Ymoving member 4 which guides the stage 2 in the X direction and issubstantially perpendicular to the X moving member 3, and a controlsection which controls the postures (e.g., the rotational displacements,translational displacements, and the like) of the X moving member 3 andY moving member 4. The control section includes linear motors 5 a and 5b which are arranged at the two ends of the X moving member 3 to drivethe X moving member 3 in the X direction, linear motors 6 a and 6 bwhich are arranged at the two ends of the Y moving member 4 to drive theY moving member 4 in the Y direction, Y guides 7 a and 7 b which guidethe Y moving member 4 in the Y direction through hydrostatic pads 8 aand 8 b, respectively, laser interferometers 9 a and 9 b which measurethe posture (e.g., the displacement in the X direction, the rotationaldisplacement in the θ z direction, and the like) of the X moving member3, and laser interferometers 10 a and 10 b which measure the posture(e.g., the displacement in the Y direction, the rotational displacementin the θ z direction, and the like) of the Y moving member 4.

The stage 2 includes, e.g., the arrangement shown in FIG. 1B. The stage2 is slidably supported by the X moving member 3 and guided along the Xmoving member 3 to move in the Y direction. The stage 2 is also slidablysupported by the Y moving member 4 and moves in the X direction alongthe Y moving member 4. The Y moving member 4 with the hydrostatic pads 8a and 8 b mounted thereon moves in the Y direction along the Y guides 7a and 7 b. The Y guides 7 a and 7 b are fixed on the surface plate 1.Permanent magnets are fixed at the two ends of the X moving member 3,and the X moving member 3 can be driven in the X direction by supplyingan electric current to the coils of the linear motors 5 a and 5 b. Sincethere are gaps between the hydrostatic pads 8 a and 8 b and the Y guides7 a and 7 b, the Y moving member 4 can rotate in the θ z direction bythe gap. In addition, the X moving member 3 can rotate in the θ zdirection by a gap between the stage 2 and the bearing.

FIG. 2 is a block diagram illustrating the arrangement of a controlsection which controls the Z-axis rotational displacements of the Xmoving member 3 and Y moving member 4 in the stage alignment apparatusaccording to the preferred embodiment of the present invention.

In FIG. 2, this control section includes, e.g., a PID controller 11which performs a control calculation such that the Y moving member 4forms a predetermined target rotation angle θz0, a PID controller 12which performs a control calculation such that the X moving member 3forms a predetermined target rotation angle θz0′, amplifiers 13 and 14which amplify electrical currents, and a filter 15 which has apredetermined frequency characteristic.

First, a rotation angle θz of the Y moving member 4 is measured by thelaser interferometers 10 a and 10 b. The difference between the measuredrotation angle θz and the target rotation angle θz0 is input to the PIDcontroller 11. The PID controller 11 performs a control signalcalculation (PID calculation) for this input using a proportional term,an integral term, and a derivative term. The amplifier 13 amplifies theoutput from the PID controller 11. The linear motors 6 a and 6 b drivethe Y moving member 4 on the basis of the output from the amplifier 13.The rotation angle θz when the Y moving member 4 is driven is measuredby the laser interferometers 10 a and 10 b, and the measurement resultis fed back to the PID controller 11. The difference between therotation angle θz, which has been measured by the laser interferometers10 a and 10 b, and the target rotation angle θz0 is also input to thefilter 15. The input is subjected to predetermined filtering andcalculation (to be described later) and then added to an input to thePID controller 12.

On the other hand, the rotation angle θ z′ of the X moving member 3 ismeasured by the laser interferometers 9 a and 9 b. The differencebetween the measured rotation angle θ z′ of the X moving member 3 andthe target rotation angle θ z0′, and that between the rotation angle θ zof the Y moving member 4 after the predetermined filtering andcalculation (to be described later) and the target rotation angle θ z0are input to the PID controller 12. The PID controller 12 performs PIDcalculation for this input. The amplifier 14 amplifies the output fromthe PID controller 12. The linear motors 5 a and 5 b drive the X movingmember 3 on, the basis of the output from the amplifier 14. The rotationangle θ z′ when the X moving member 3 is driven is measured by the laserinterferometers 9 a and 9 b, and the measurement result is fed back tothe PID controller 12. In this manner, since the difference between therotation angle θ z of the Y moving member 4 and the target rotationangle θ z0 is input to the PID controller 12, the X moving member 3 canmove in accordance with the control result for the Y moving member 4.

In this embodiment, though calculation of the differences between therotation angles of the X moving member 3 and Y moving member 4 and thetarget rotation angle, calculation by the PID controllers 11 and 12, andcalculation by the filter 15 are implemented as software on a computer,the present invention is not limited to this. Part or all of thesecalculations may be implemented by hardware including at least one of ananalog arithmetic element and a digital arithmetic element.

FIG. 3 is a graph showing a frequency characteristic of the filter 15shown in FIG. 2. The filter 15 is designed to suppress, e.g., frequencycomponents higher than a predetermined frequency f0 of a signalindicating the rotational displacement of the Y moving member 4. Thiscan eliminate extra high-frequency components generated in a signalindicating the rotational displacement of the Y moving member 4 tocontrol the X moving member 3 more precisely.

FIG. 4 is a graph showing a frequency characteristic of the filter 15,which is different from that shown in FIG. 3. The filter 15 can causethe X moving member 3 to track the Y moving member 4 at further higherprecision by setting a peak value h1 and a frequency f1 of a frequencyresponse in accordance with the values h1 and f1 of the frequencyresponse of a signal indicating the target rotation angle of the Xmoving member 3.

Additionally, a situation wherein the X moving member 3 is pressedagainst the bearing with excessive force can be avoided by setting thecoefficient of the integral term of the PID controller 12 to zero toobviate the need to perform integral calculation.

As described above, according to the preferred embodiment of the presentinvention, by improving a controller without an increase in complexityof the apparatus by addition of a mechanical element to a moving member,any excessive constraint which may occur between the moving member and astage and any vibrations caused by this constraint can be avoided. Acontroller according to the preferred embodiment of the presentinvention can be implemented at a low cost by software.

A signal for controlling the posture (e.g., the rotational displacement,translational displacement, and the like) of the first moving member isinput to a control system which controls the posture (e.g., therotational displacement, translational displacement, and the like) ofthe second moving member to allow a change in tracking performance ofthe second moving member. For example, the frequency response of afilter is set in accordance with the peak value and the frequency of thefrequency response in an output signal from the control system whichcontrols the second moving member, so that the second moving member canfollow the first moving member further precisely.

[Second Embodiment]

FIG. 5 is a block diagram showing the arrangement of a control sectionwhich controls the Z-axis rotational displacements of an X moving member3 and a Y moving member 4 in a stage alignment apparatus according tothe second preferred embodiment of the present invention. The samereference numerals denote the parts similar to those in the firstembodiment. The difference from the first embodiment lies in that afilter 16 with a predetermined frequency characteristic is provided. Thefilter 16 performs predetermined calculation for a signal indicating thedifference between a rotation angle θ z′ of the X moving member 3 and atarget rotation angle θ z0′, and the calculation result is added to aninput to a PID controller 11. This can cause the Y moving member 4 totrack the X moving member 3 when a rotational displacement occurs in theX moving member 3, as in a case wherein the X moving member 3 is made totrack the Y moving member 4 when a rotational displacement occurs in theY moving member 4 in FIG. 2.

[Other Embodiment]

An embodiment in which a stage alignment apparatus according to thepresent invention is applied to an exposure apparatus used in themanufacturing process of a semiconductor device will be described next.

FIG. 6 shows the concept of an exposure apparatus used when a stagealignment apparatus according to the present invention is applied to themanufacturing process of a semiconductor device.

An exposure apparatus 60 according to a preferred embodiment of thepresent invention is comprised of an illumination optical system 61, areticle 62, a projection optical system 63, a substrate 64, and a stage65. The illumination optical system 61 can employ, as exposure light,e.g., ultraviolet rays which use an excimer laser, a fluorine excimerlaser, or the like, as a light source. Light emitted from theillumination optical system 61 illuminates the reticle 62. The lighthaving passed through the reticle 62 is focused on the substrate 64through the projection optical system 63 to expose a photosensitivemember applied on the substrate 64. The substrate 64 is moved to apredetermined position by the stage 65 using the stage alignmentapparatus according to the preferred embodiment of the presentinvention.

FIG. 7 shows the flow of the whole manufacturing process of thesemiconductor device using the above-mentioned exposure apparatus. Instep 1 (circuit design), a semiconductor device circuit is designed. Instep 2 (mask formation), a mask having the designed circuit pattern isformed. In step 3 (wafer manufacture), a wafer is manufactured by usinga material such as silicon. In step 4 (wafer process), called apreprocess, an actual circuit is formed on the wafer by lithographyusing the prepared mask and wafer. Step 5 (assembly), called apost-process, is the step of forming a semiconductor chip by using thewafer formed in step 4, and includes an assembly process (dicing andbonding) and a packaging process (chip encapsulation). In step 6(inspection), the semiconductor device manufactured in step 5 undergoesinspections such as an operation confirmation test and a durabilitytest. After these steps, the semiconductor device is completed andshipped (step 7).

FIG. 8 shows the detailed flow of the above-mentioned wafer process. Instep 11 (oxidation), the wafer surface is oxidized. In step 12 (CVD), aninsulating film is formed on the wafer surface. In step 13 (electrodeformation), an electrode is formed on the wafer by vapor deposition. Instep 14 (ion implantation), ions are implanted in the wafer. In step 15(resist processing), a photosensitive agent is applied to the wafer. Instep 16 (exposure), the wafer is moved at high precision using theabove-mentioned exposure apparatus, and the circuit pattern istransferred onto the wafer. In step 17 (development), the exposed waferis developed. In step 18 (etching), the resist is etched except for thedeveloped resist image. In step 19 (resist removal), an unnecessaryresist after etching is removed. These steps are repeated to formmultiple circuit patterns on the wafer.

With the above-mentioned process, any vibrations which may occur uponstage movement in the exposure step are suppressed, and thus a circuitpattern can be transferred onto a wafer at higher precision.

According to the present invention, by, e.g., controlling the posture ofthe second moving member on the basis of a signal for controlling theposture of the first moving member, a stage alignment apparatus, whichprecisely moves a stage and its control method, an exposure apparatusand a semiconductor device manufacturing method, can be provided.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the claims.

1. A stage alignment apparatus comprising: a first moving member whichmoves in a first direction; a second moving member which moves in asecond direction different from the first direction; a stage which isslidably supported by said first moving member and said second movingmember and is guided in the first and second directions; a first controlsection which controls a posture of said first moving member in a thirddirection, the third direction being a direction rotatable about an axissubstantially perpendicular to the first and second directions; and asecond control section which controls a posture of said second movingmember in the third direction on the basis of a signal which controlsthe posture of said first moving member in the third direction.
 2. Theapparatus according to claim 1, wherein each of said first controlsection and said second control section has: a measurement section whichmeasures the posture of a respective moving member; and an actuatorwhich drives a respective moving member on the basis of a measurementresult obtained by said measurement section.
 3. The apparatus accordingto claim 2, wherein the actuator comprises a linear motor.
 4. Theapparatus according to claim 1, wherein said second control sectioncontrols the posture of said second moving member on the basis of asignal which controls the posture of the first moving member filtered bya predetermined filter.
 5. The apparatus according to claim 1, whereinsaid first moving member and said second moving member are supported byguides arranged such that their ends are parallel to the first andsecond directions, respectively, and a bearing which slides with apredetermined gap that allows rotational displacement in the thirddirection with respect to the guides and are guided in the first andsecond directions through the guides and bearing.
 6. The apparatusaccording to claim 1, wherein said first control section performscalculations of a proportional term, an integral term, and a derivativeterm to obtain a signal which controls the posture of said first movingmember, and said second control section performs calculations of aproportional term and derivative term to obtain the posture of saidsecond moving member.
 7. The apparatus according to claim 1, whereinsaid first control section controls the posture of said first movingmember on the basis of a signal which controls the posture of saidsecond moving member.
 8. A method of controlling a stage alignmentapparatus for guiding a stage in a first direction and a seconddirection different from the first direction by a first moving memberwhich can move in the first direction and a second moving member whichcan move in the second direction, said method comprising: a step ofmoving the first moving member in a third direction, the third directionbeing a direction rotatable about an axis substantially perpendicular tothe first and second directions; and a step of controlling a posture ofthe second moving member in the third direction on the basis of a signalwhich controls the posture of the first moving member in the thirddirection.
 9. The method according to claim 8, wherein in the firstcontrol step, the posture of the first moving member is controlled onthe basis of a signal which controls a posture of the second movingmember.
 10. A semiconductor device manufacturing method comprising: acoating step of coating a substrate with a photosensitive member; anexposure step of transferring a pattern onto the substrate coated withthe photosensitive member; an exposure step of transferring a patternonto the substrate coated with the photosensitive member in the coatingstep using a method of controlling a stage alignment apparatus accordingto claim 8; and a development step of developing the photosensitivemember of the substrate on which the pattern is transferred in saidexposure step.
 11. A stage alignment apparatus comprising: a stage; afirst guiding member which guides said stage in a first direction; asecond guiding member which guides said stage in a second directionperpendicular to the first direction; a first driving member whichdrives said first guiding member in a direction rotatable about an axissubstantially perpendicular to the first and second directions and inthe second direction; a second driving member which drives said secondguiding member in the rotatable direction and in the first direction;and a control member which controls said first driving member and saidsecond driving member, wherein said control member controls a rotationof said second guiding member on the basis of a signal which controlsthe rotation of said first guiding member.
 12. The apparatus accordingto claim 11, further comprising: a first measurement member whichmeasures a position of said first guiding member in the rotatabledirection; and a second measurement member which measures a position ofsaid second guiding member in the rotatable direction.
 13. The apparatusaccording to claim 11, further comprising: a first linear motor arrangedat both ends of said first guiding member; and a second linear motorarranged at both ends of said second guiding member.
 14. The apparatusaccording to claim 11, wherein the signal is filtered.
 15. The apparatusaccording to claim 11, further comprising: a base which supports saidstage; and a guide which is fixed on said base, wherein at least one ofsaid first guiding member and said second guiding member is guided bysaid guide through bearings.
 16. An exposure apparatus comprising: anexposure member for transferring a pattern onto a substrate; and a stagefor moving said substrate, wherein said stage is aligned by saidapparatus according to claim
 11. 17. A device manufacturing methodcomprising: a step of transferring a pattern onto the substrate by usingthe exposure apparatus according to claim 16; and a step of developingthe transferred pattern.